GÖKYÜZÜNDEKİ INTERNET'İN SORUNLARI

 

Internet'in iyimser tahminleri bile geride bırakan bir ivmeyle yaygınlaşması, sunulan hizmetlerin çeşitlenmesi ve insan yaşamının hemen her alanında bir gereklilik olarak belirmesi, farklı iletişim olanaklarının bu yönde kullanılmasını gündeme getirmiştir. Bunlar arasında en güncel olanlardan biri, uydu iletişiminden Internet'in sağladığı hizmetler için bir altyapı oluşturacak yönde yararlanılmasıdır. Yeryüzünü bütünleyen bir ağ da gökyüzünde kurulmaktadır denebilir.

Internet trafiği, gerek kullanıcıların Internet'e erişim olanaklarında var olan çeşitlilikten, gerek veri istem ve sunumuna verilen ağırlıktan gerekse de istemde bulunulan verinin yapısından ortaya çıkan farklılıklardan ötürü heterojen bir yapı göstermektedir. Bu trafik, TCP/IP kalıbının içinde yeralmaktadır.

Öte yanda, uydu iletişimi, Internet açısından olumlu ve olumsuz karakteristikler taşımaktadır. Olumlu karakteristiklerini öne alan iletişim trafiğine uygun Internet servislerinde Internet'e ve ilişkili ağ servislerine önemli katkılar getireceği güvenle söylenebilir. Gerekirse halen var olan tekniklerde modifikasyonlar yapılmaya çalışılmaktadır. Bu konudaki çalışmalara ilişkin yayınlardan bir liste aşağıda verilmiştir:

 
Mark Allman.
Improving TCP Performance Over Satellite Channels.
M.Sc. thesis, Ohio University, June 1997.
M. Allman.
Fixing Two BSD TCP Bugs.
Technical Report CR-204151, NASA Lewis Research Center. October 1997.
 
M. Allman.
An Evaluation of TCP with Larger Initial Windows.
40th IETF Meeting -- TCP Implementations WG. December, 1997. Washington, DC.
 
M. Allman, Jim Griner, Hans Kruse, Diepchi Tran.
HTTP Page Transfer Rates Over Geo-Stationary Satellite Links.
Proceedings of the Sixth International Conference on Telecommunication Systems. March 1998.
 
M. Allman, Chris Hayes, H. Kruse, Shawn Ostermann.
TCP Performance Over Satellite Links.
Proceedings of the 5th International Conference on Telecommunication Systems, March 1997.
 
M. Allman, H. Kruse, S. Ostermann.
An Application-Level Solution to TCP's Satellite Inefficiencies.
Proceedings of the First International Workshop on Satellite-based Information Services (WOSBIS), November
1996.
 
M. Allman, H. Kruse, S. Ostermann.
Data Transfer Efficiency Over Satellite Circuits Using a Multi-Socket Extension to the File Transfer Protocol (FTP).
Proceedings of the ACTS Results Conference, NASA Lewis Research Center, September 1995.
 
Vivek Arara, John S. Baras, Douglas Dillon, Narin Suphasindhu.
Asymmetric Internet Access Over Satellite-Terrestrial Networks.
Proceedings of the AIAA: 16th International Communications Satellite Systems Conference and Exhibit, Part1,
pp. 476-482, Washington, D.C, February 25-29, 1996.
 
B.R. Badrinath, Ajay Bakre.
I-TCP: Indirect TCP for Mobile Hosts.
Proceeding of the 15th International Conference on Distributed Computing Systems (ICDCS), May 1995.
 
Hari Balakrishnan, Randy H. Katz, Venkata N. Padmanabhan.
The Effects of Asymmetry on TCP Performance.
Proceedings of the ACM/IEEE Mobicom, Budapest, Hungary, ACM. September, 1997.
H. Balakrishnan, R. H. Katz, V. N. Padmanabhan, Srinivasan Seshan.
A Comparison of Mechanism for Improving TCP Performance over Wireless Links.
IEEE/ACM Transactions on Networking, December 1997.
 
David Borman, Robert Braden, Van Jacobson.
TCP Extensions for High Performance, May 1992. RFC 1323.
 
R. Braden.
Requirements for Internet Hosts -- Communication Layers, October 1989. RFC 1122.
R. Braden.
Transaction TCP -- Concepts, September 1992. RFC 1379.
 
R. Braden.
T/TCP -- TCP Extensions for Transactions: Functional Specification, July 1994. RFC 1644.
 
Steve Deering, Jeff Mogul.
Path MTU Discovery, November 1990. RFC 1191.
 
Kevin Fall, Sally Floyd.
Simulation-based Comparisons of Tahoe, Reno and SACK TCP.
Computer Communication Review, July 1996.
 
S. Floyd, Jamshid Mahdavi, Matt Mathis, Allyn Romanow.
TCP Selective Acknowledgment Options, October 1996. RFC 2018.
 
Jonathan Hahn.
MFTP: Recent Enhancements and Performance Measurements.
Technical Report RND-94-006, NASA Ames Research Center, June 1994.
 
C. Hayes.
Analyzing the Performance of New TCP Extensions Over Satellite Links.
M.Sc. Thesis, Ohio University, August 1997.
 
John Heidemann, Vikram Visweswaraiah.
Improving Restart of Idle TCP Connections.
Technical Report 97-661, University of Southern California, 1997.
J. Heidemann, V. Visweswaraiah.
Rate-based pacing Source Code Distribution.
http://www.isi.edu/lsam/publications/rate_based_pacing/README.html. November, 1997.
 
Janey Hoe.
Improving the Startup Behavior of a Congestion Control Scheme for TCP.
ACM SIGCOMM, August 1996.
 
David Iannucci, John Lakashman.
MFTP: Virtual TCP Window Scaling Using Multiple Connections.
Technical Report RND-92-002, NASA Ames Research Center, January 1992.
 
Van Jacobson.
Modified TCP Congestion Avoidance Algorithm. Technical Report, LBL, April 1990.
 
V. Jacobson.
Congestion Avoidance and Control.
Proceedings of the SIGCOMM '88, ACM. August, 1988.
V. Jacobson.
Compressing TCP/IP Headers, February 1990. RFC 1144.
 
V. Jacobson, Michael Karels.
Congestion Avoidance and Control.
ACM SIGCOMM, 1988.
 
V. Jacobson, M. Karels.
Congestion Avoidance and Control.
ftp://ftp.ee.lbl.gov/papers/congavoid.ps.Z.'den sağlanabilir. 1992.
 
Stacy Johnson.
Increasing TCP Throughput by Using an Extended Acknowledgment Interval.
M.Sc. Thesis, Ohio University, June 1995.
 
Srinivasan Keshaw.
A Control Theoretic Approach to Flow Control.
ACM SIGCOMM, September 1991.
 
S. Keshaw, S. Morgan.
SMART Retransmission: Performance with Overload and Random Losses.
Proceeding of Infocom. 1997.
 
Steve Knowles.
IESG Advice from Experience with Path MTU Discovery, March 1993. RFC 1435.
 
James Martin.
Communications Satellite Systems.
Prentice Hall, 1978.
 
Jamshid Mahdavi, Matt Mathis.
Forward Acknowledgment: Refining TCP Congestion Control.
ACM SIGCOMM, 1996.
 
Kathleen Nichols.
Improving Network Simulation with Feedback.
Com21, Inc. Technical Report. http://www.com21.com/pages/papers/068.pdf'den sağlanabilir.
 
Craig Partridge, Tim Shepard.
TCP Performance Over Satellite Links.
IEEE Network, 11(5), September/October 1997.
 
Vern Paxson.
Automated Packet Trace Analysis of TCP Implementations.
Proceedings of ACM SIGCOMM, September 1997.
 
Jon Postel.
Transmission Control Protocol, September 1981. RFC 793.
 
William Stallings.
Data and Computer Communications.
MacMillian, 4th edition, 1994.
 
W. Richard Stevens.
TCP Slow Start, Congestion Avoidance, Fast Retransmit, and Fast Recovery Algorithms.
January 1997. RFC 2001.
 
J. Touch.
TCP Control Block Interdependence.
RFC-2140, USC/Information Sciences Institute , April 1997.
 

(Ar-Ge 13/07/1998)